What I want is a service that will let me upload a few GB of data and be sure of being able to get it back at an arbitary time in the future. I don't need high bandwith or the ability to make it globally accessible, but do need a reasonable amount of storage and a guarantee of data integrity. I'd be willing to pay a reasonable rate for this.

(It has been suggested that a good solution is creating yourself a bunch of gmail accounts and mailing yourself the data).